Why post editor says connection lost time to time ?

My website (onlinejuction.com) was running smoothly while using 4.4. After upgrading to 4.5 I am having very serious problem. My problem is that, it shows time to time connection lost notice and goes on time out or 500 error even if I am using 3-5 Mbps network. I can restore, my content after refreshing but time to time I have to enter tag, category, seo keyword, fractured image, and so on. What might be main causes of the problem ? My another website of same host is running smoothly.